Complimentary bar's last to open (4)
I believe the answer is:
free
'complimentary' is the definition.
(synonyms)
'bar's last to open' is the wordplay.
I cannot really understand how this works, but
'last' could be 'f' (I've seen this in other clues) and 'f' is found in the answer.
The remaining letters 'ree' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for free that I've seen before include "Unconfined" , "Not employed" , "At large" , "without payment" , "At liberty" .)