Invest when carried up East (6)
I believe the answer is:
enrobe
'invest' is the definition.
(thesaurus)
'carried up east' is the wordplay.
'carried' becomes 'borne' (I've seen this in another clue).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'east' becomes 'E' (synonyms).
'borne' written backwards gives 'enrob'.
'enrob'+'e'='ENROBE'
'when' is the link.
(Other definitions for enrobe that I've seen before include "Fancy" , "Dress, put on vestments" , "Don a vestment" , "make investment?" , "Clad ceremonially" .)