King inclined to be fascinated (4)
I believe the answer is:
rapt
'be fascinated' is the definition.
(I've seen this before)
'king inclined' is the wordplay.
'king' becomes 'r' (r is abbreviation for rex).
'inclined' becomes 'apt' ('apt' can be similar in meaning to 'inclined').
'r'+'apt'='RAPT'
'to' is the link.
(Other definitions for rapt that I've seen before include "Delighted" , "Ecstatic - engrossed" , "Ecstatic in part" , "Fully absorbed" , "Spellbound, enthralled" .)