Working men in drink get tight (5,2)
I believe the answer is:
screw up
'get tight' is the definition.
I can't tell whether this definition defines the answer.
'working men in drink' is the wordplay.
'working men' becomes 'crew' (I've seen this in other clues. I am not sure about the 'working' bit.).
'in' means one lot of letters goes inside another.
'drink' becomes 'sup' (to sup is to drink).
'crew' going into 'sup' is 'SCREW-UP'.
Can you help me to learn more?
(Other definitions for screw up that I've seen before include "Make a mess of, ruin" , "Fail badly" , "Disastrous failure" , "Mishandle a situation" , "Make a mess of things" .)