Hearts card seen ahead of the turn, finally? Raise! (8)
I believe the answer is:
heighten
'raise' is the definition.
(synonyms)
'hearts card' is the wordplay.
'hearts' becomes 'heigh' (I am not sure about this - if you are sure you should believe this answer much more).
'card' becomes 'ten' (eg ten of spades).
'heigh'+'ten'='HEIGHTEN'
'seen ahead of the turn finally?' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for heighten that I've seen before include "Lift" , "Elevate - intensify" , "Raise" , "Intensify; make taller" , "Increase in amount of degree" .)