Slip into Henley? (3)
I believe the answer is:
don
This clue could be a double definition.
'slip into' is the first definition.
(I've seen this before)
'henley?' is the second definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I can't see?
Can you help me to learn more?
(Other definitions for don that I've seen before include "River, academic" , "Put on for the Mafia chief and Spanish aristocrat" , "Mafia chief or Spanish title" , "Spanish nobleman" , "Put on; college teacher" .)