Lag finally escaped lock-up (5)
I believe the answer is:
delay
'lag' is the definition.
(I've seen this before)
'finally escaped lock-up' is the wordplay.
'finally' says to take the final letters.
'lock' becomes 'yale' (I've seen this before**).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
The final letter of 'escaped' is 'd'.
'yale' in reverse letter order is 'elay'.
'd'+'elay'='DELAY'
(Other definitions for delay that I've seen before include "Put off; pause" , "Defer; make late" , "Hinder" , "Hold-up, time lag" , "Stoppage" .)