Single, going round clubs in the past (4)
I believe the answer is:
once
'in the past' is the definition.
(I've seen this before)
'single going round clubs' is the wordplay.
'single' becomes 'one' (I've seen this before).
'going round' means one lot of letters goes inside another.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'one' placed around 'c' is 'ONCE'.
(Other definitions for once that I've seen before include "in bygone days" , "not repeatedly" , "On a single (or past) occasion" , "in days of yore?" , "In the old days" .)