Coy nurse trained guiding light (8)
I believe the answer is:
'guiding light' is the definition.
'coy nurse trained' is the wordplay.
'trained' indicates an anagram (to train can mean to grow something into a shape).
'coynurse' is an anagram of 'CYNOSURE'.
(Other definitions for cynosure that I've seen before include "Irresistible sight" , "Centre of attraction" , "Focus of attention" , "major attraction" , "that attracts attention" .)