Extend a term of imprisonment (7)
I believe the answer is:
stretch
I believe this clue is a double definition.
'extend' is the first definition.
(I know that extend can be written as stretch)
'a term of imprisonment' is the second definition.
(a stretch of jail time)
(Other definitions for stretch that I've seen before include "Extend, elongate" , "extended" , "Physical exercise" , "Draw out" , "Make demands on; continuous expanse" .)