Inappropriate female introduced to squad (5)
I believe the answer is:
unfit
'inappropriate' is the definition.
(I've seen this before)
'female introduced to squad' is the wordplay.
'female' becomes 'f' (common abbreviation).
'introduced to' means one lot of letters goes inside another.
'squad' becomes 'unit' (I've seen this before).
'f' inserted into 'unit' is 'UNFIT'.
(Other definitions for unfit that I've seen before include "struggling to keep up?" , "Not healthy" , "Inapt" , "In bad physical condition" , "Ill-equipped" .)