Occasionally, mind recalls model (5)
I believe the answer is:
ideal
'model' is the definition.
(ideal can mean model or perfect)
'occasionally mind recalls' is the wordplay.
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'mind'+'recalls'='mindrecalls'
The alternate letters of 'mindrecalls' are 'IDEAL'.
(Other definitions for ideal that I've seen before include "Standard of perfection or excellence" , "fanciful" , "existing only in imagination" , "A deli (anag.)" , "Perfect but perhaps unlikely to become reality" .)