Run into old flame with passionate urge (6)
I believe the answer is:
exhort
'urge' is the definition.
('exhort' can be a synonym of 'urge')
'run into old flame with passionate' is the wordplay.
'run' becomes 'r' (cricket abbreviation).
'into' indicates putting letters inside.
'old flame' becomes 'ex' (I've seen this in other clues).
'with' means one lot of letters go next to another.
'passionate' becomes 'hot' ('hot' can be similar in meaning to 'passionate').
'ex'+'hot'='exhot'
'r' placed into 'exhot' is 'EXHORT'.
(Other definitions for exhort that I've seen before include "Call" , "Spur on" , "Encourage, urge" , "Strongly urge (someone to do something)" , "Urge, counsel earnestly" .)