Pick up huge contract (7)
I believe the answer is:
tighten
'contract' is the definition.
(I've seen this before)
'pick up huge' is the wordplay.
'pick up' shows a homophone (sound like) (I've seen 'picked up' mean this).
'huge' becomes 'titan' (I've seen this before).
'titan' is a homophone of 'TIGHTEN'.
(Other definitions for tighten that I've seen before include "Do this to your belt to economise (7)" , "To improve focus" , "Become more tense" , "increase tension" , "contract" .)