A, pleasant, excellently crafted, puzzle a little on the easy side of average for me.
Solving time: 14 mins
* =anagram
ACROSS
5 MAGICIAN GI in maniac* Joe is US usage for a soldier i.e. GI
9 PETIT(e) I(r)ON Nancy being a French city – you often see Nice used in clues for that also.
11 BEEF BURGER Re grub reversed Very good and amusing.
12 O B O Examine O O stands for the specs
16 CADDIE (addic)* collapsE
17 A N GO (L) A A little surprised to see Goa defined as tourist destination but it must be.
19 SAN (CT) ITY
21 DALI My last one – always nervous with 4-letter answers, where both crossing letters are vowels. But, it came quickly enough in the end Il(i)ad reversed.
27 ETHER E (A) L Number = ether i.e. something that numbs el = the in Spanish a = area
DOWN
3 GRIEF (figure)* less u
4 T (RIB) UNE Excellent play with the meaning of words here, which reminded me of Mass puzzles.
5 M AN AGE R The outskirts are the first and last letters.
7 CO NCORDAT (Car don’t)* An excellent, and amusing, surface reading.
8 A POLO GIST
14 HANG A(r)BOUT
15 ABOMINATE “A bomb in eight”! 100/8 = 12.5
23 NO TED (Heath)
I agree: pleasant, uncontroversial stuff for a Monday, and I also liked the clue for TRIBUNE