Run into old flame with passionate urge (6)
I believe the answer is:
Here is my best explanation:
'urge' is the definition.
('exhort' can be a synonym of 'urge')
'run into old flame with passionate' is the subsidiary indication.
'run' becomes 'r' (cricket abbreviation).
'into' means one lot of letters goes inside another.
'old flame' becomes 'ex' (I've seen this in other clues).
'with' is a charade indicator (letters next to each other).
'passionate' becomes 'hot' ('hot' can be similar in meaning to 'passionate').
'r' inserted within 'exhot' is 'exhort'.
(Other definitions for exhort that I've seen before include "To urge", "Counsel", "Strongly advise", "Command", "Strongly urge (someone to do something)", "Urge strongly and sincerely", "Advise strongly", "Spur on", "Give great encouragement to" and "Urge, advise earnestly".)