60 minutes showing no opening for us (3)
I believe the answer is:
our
'for us' is the definition.
(I've seen this in another clue)
'60 minutes showing no opening' is the wordplay.
'60 minutes' becomes 'hour' (synonyms).
'showing no opening' means to remove the first letter.
'hour' with its initial letter taken away is 'OUR'.
(Other definitions for our that I've seen before include "Yours and mine" , "''Now is the winter of ... discontent'' (Richard III)" , "group possession?" , "Relating to us" , "Belonging to us" .)