Husband involved in manoeuvre for some time (5)
I believe the answer is:
while
'for some time' is the definition.
(a while is a period of time)
'husband involved in manoeuvre' is the wordplay.
'husband' becomes 'h'.
'involved in' means one lot of letters goes inside another.
'manoeuvre' becomes 'wile' (both can mean a ploy or clever strategy).
'h' placed into 'wile' is 'WHILE'.
(Other definitions for while that I've seen before include "Whereas" , "Space of time" , "During the time that, as long as" .)