Keener for regulars to join hem for blue dress (6)
I believe the answer is:
enrobe
'blue dress' is the definition.
'enrobe' can be an answer for 'dress' (I've seen this before). I'm unsure of the 'blue' bit.
'keener for regulars to join hem' is the wordplay.
'regulars' means one should take alternating letters (letters selected at regular intervals).
'to join hem' becomes 'be' (I am not sure about this - if you are sure you should believe this answer much more).
'keener'+'for'='keenerfor'
The alternating letters of 'keenerfor' are 'enro'.
'enro'+'be'='ENROBE'
'for' is the link.
Can you help me to learn more?
(Other definitions for enrobe that I've seen before include "Dress, put on vestments" , "put on gown" , "put on formally ..." , "make investment?" , "Don a vestment" .)