Record single rising — around number four in chart (5)
I believe the answer is:
enrol
'record' is the definition.
(I've seen this before)
'single rising around number four in chart' is the wordplay.
'single' becomes 'lone' (synonyms).
'rising' shows that the letters should be reversed in order (going up in a down clue).
'around' indicates putting letters inside.
'number four in chart' becomes 'r' (4th letter of 'chart').
'lone' reversed gives 'enol'.
'enol' placed around 'r' is 'ENROL'.
(Other definitions for enrol that I've seen before include "Enter" , "Register (as student)" , "Sign on, register" , "Join as member" , "Add to list of members" .)