Squad's days in custody (5)
I believe the answer is:
cadre
'squad's' is the definition.
(thesaurus)
'days in custody' is the wordplay.
'days' becomes 'd'.
'in' is an insertion indicator.
'custody' becomes 'care' (I've seen this before).
'd' put within 'care' is 'CADRE'.
(Other definitions for cadre that I've seen before include "Group of revolutionaries" , "Nucleus of trained fighters" , "Raced around the framework of a military unit" , "Group of key people" , "Raced around with group" .)