Cool evangelist, friendly (8)
I believe the answer is:
lukewarm
'cool' is the definition.
(thesaurus)
'evangelist friendly' is the wordplay.
'evangelist' becomes 'luke' (I have seen 'Biblical evangelist' mean 'luke' so perhaps 'evangelist' could also mean 'luke').
'friendly' becomes 'warm' (associated in meaning).
'luke'+'warm'='LUKEWARM'
(Other definitions for lukewarm that I've seen before include "Rather cool" , "Tepid, or less than enthusiastic" , "Not enthusiastic, neither hot nor cold" , "Unenthusiastic" , "Half-hearted" .)