Squash up, then continue (5,5)
I believe the answer is:
press ahead
'continue' is the definition.
(to press ahead is to continue or carry on)
'squash up' is the wordplay.
'squash' becomes 'press' (I've seen this in other clues).
'up' becomes 'ahead' (similar in meaning).
'press'+'ahead'='PRESS AHEAD'
'then' is the link.
(Other definitions for press ahead that I've seen before include "Continue regardless" , "Keep on" , "Go on" , "carry on in spite of opposition" , "Move forward" .)