Make longer time in clink (7)
I believe the answer is:
stretch
This might be a double definition.
'make longer' is the first definition.
(stretching is a kind of making longer)
'time in clink' is the second definition.
'stretch' can be an answer for 'time' (I've seen this before). I'm not certain of the 'in clink' bit.
Can you help me to learn more?
(Other definitions for stretch that I've seen before include "Time lag's got" , "Continuous expanse/period" , "Make demands on; continuous expanse" , "Increase" , "Extend, time spent in prison" .)