Daydream about tan den? (5,5)
I believe the answer is:
brown study
'daydream' is the definition.
(thesaurus)
'tan den?' is the wordplay.
'tan' becomes 'brown' (I've seen this before).
'den?' becomes 'study' (I've seen this before).
'brown'+'study'='BROWN STUDY'
'about' is the link.
(Other definitions for brown study that I've seen before include "Contemplative reverie" , "Deep reverie" , "Deep thoughtfulness" .)