PETO kicks off the week…
An enjoyable puzzle with a couple of new ones for me (5d and 20a).
Thanks PETO

ACROSS
1. Offsets the effects of Communist writer needing to satisfy Stalin primarily (11)
COMPENSATES
COM (Communist) + PEN (writer) needing SATE (to satisfy) + S[talin] (primarily)
9. Academic, a short time after, left to get port (5)
MALMO
MA (academic) + (MO (a short time) after L (left))
10. Nothing found in lined bra used as an ammunition carrier (9)
BANDOLIER
O (nothing) found in (LINED BRA)* (*used)
11. Following advice enrol a number on the way back? Grand (9)
LISTENING
LIST (enrol) + (NINE)< (a number, <on the way back) + G (grand)
12. Plant last of evidence before broadcast about implicating Colombian leader (5)
ERICA
[evidenc]E (last of) before (AIR)< (broadcast, <about) implicating C[olumbian] (leader)
13. Fate of criminal once finding work absorbing in that place? On the contrary (3,4)
THE ROPE
OP (work) absorbing THERE (in that place), on the contrary
15. Musician’s vibrator found in study I hear (4)
REED
"read" = REED (study, "I hear")
18. Resolutely oppose ignoring daughter’s support (4)
BEAR
BEAR[d] (resolutely oppose, ignoring D (daughter))
20. Excessive to intervene in free love as a public entertainment in the past (7)
RIDOTTO
OTT (excessive) to intervene in (RID (free) + O (love))
23. Start without a midday meal (5)
LUNCH
L[a]UNCH (start, without A)
24. Take out language proceeding from fear at the outset (6,3)
POLISH OFF
POLISH (language) + OF (proceeding from) + F[ear] (at the outset)
26. Extremely volatile converted realist of many sided ability (9)
VERSATILE
V[olatil]E (extremely) + (REALIST)* (*converted)
27. Site of siege and massacre a month after the French return (5)
ALAMO
(A + MO (month)) after (LA)< (the, French, <return)
28. Town’s bread maker (3)
RYE
29. Deus ex machina perhaps causing present outcome (5,6)
STAGE EFFECT
STAGE (present) + EFFECT (outcome)
DOWN
1. Fully equipped to contend for a prize around the end of April (8)
COMPLETE
COMPETE (contend for a prize) around [apri]L (end of)
2. Missouri girls making treacle (8)
MOLASSES
MO (Missouri) + LASSES (girls)
3. Wear away strip essentially against European opposition opening with Germany and Spain (5)
ERODE
([st]R[ip] (essentially) against E (European)) + O[pposition] (opening) with D (Germany) and E (Spain)
4. Cave in Southern Belgium penetrated by university team (7)
SUBSIDE
((S (southern) + B (Belgium)) penetrated by U (university)) + SIDE (team)
5. Flier showing volunteers facing half- hearted moaner (7)
TANAGER
TA (volunteers) facing NAG[g]ER (moaner, half-hearted)
6. Went, after having no doubt reportedly, for an aquatic perennial (9)
SHOREWEED
WEED (went) after "sure" = SHORE (having no doubt, "reportedly")
7. Piece regularly dismissed after endless quote about back of door knocker (6)
CRITIC
[p]I[e]C[e] (regularly dismissed) after (CIT[e] (quote, endlessly) about [doo]R (back of))
8. About to block not this but the other source of danger (6)
THREAT
RE (about) to block THAT (not this but the other)
14. In excess of principal’s expenses (9)
OVERHEADS
OVER (in excess of) + HEADS (principal's)
16. Become pale finding American in fancy toilet cubicle at last (8)
ETIOLATE
A (american) in (TOILET)* (*fancy) + [cubicl]E (at last)
17. Impudence seen on prisoner’s face (8)
CONFRONT
FRONT (impudence) seen on CON (prisoner)
19. Copy in Erica struggling to grasp programming language (7)
REPLICA
(ERICA)* (*struggling) to grasp PL (programming language)
20. Priest interrupting continually sent up with ease (7)
RELIEVE
ELI (priest) interrupting (EVER)< (continually, <sent up)
21. Cunning Conservative joins party on the rise (6)
CLEVER
C (Conservative) joins (REVEL)< (party, <on the rise)
22. False dawn finally admitted by United faithful (6)
UNTRUE
[daw]N (finally) admitted by (U (united) + TRUE (faithful))
25. Remain unfinished needing fellows in support (5)
STAFF
STA[y] (remain, unfinished) needing F F (fellows)
Fun although I couldn’t do much with the SE corner, and Tanager was a NHO.
I enjoyed Compensate, Versatile and Overheads.
Thanks to Peto and Teacow
Even though I now understand the parsing of 13a (THE ROPE) I could not do the mental gymnastics on my own to figure out the solve . . . I had THE -O-E . . . It’s not quite a Doh! – Otherwise I was stuck in the NW until I suddenly saw the very obvious MOLASSES (definitely a Doh!) and everything then fell into place. Thanks etc.
Enjoyable. I had the same NHOs as Teacow and proudly wrote them in from the wordplay.
Liked bandolier, and lunch, and thought clever was clever.
Thanks Peto for an enjoyable crossword. My top picks were LUNCH, ALAMO, MOLASSES, SUBSIDE, & CLEVER. The nho RIDOTTO was clear enough from the wordplay. I questioned ‘used’ as an anagram indicator in 10a but almost any word seems to be fair game for this device in some circles. Another question I had was ‘showing’ linking definition to wordplay in 5d; generally the wordplay ‘shows’ the definition in my mind. Thanks Teacow for the blog.