Not appropriate having some lieutenant panicking in retreat (5)
I believe the answer is:
inapt
'not appropriate' is the definition.
(inapt means inappropriate or ill-fitting)
'some lieutenant panicking in retreat' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'in retreat' is a reversal indicator.
'tpani' is hidden in the letters of 'lieutenant panicking'.
'tpani' back-to-front is 'INAPT'.
'having' is the link.
(Other definitions for inapt that I've seen before include "Useless" , "not seemly" , "It's clumsy" , "Inappropriate" , "Out of place" .)