Praise twofold on way back (4)
I believe the answer is:
laud
'praise' is the definition.
(I know that laud is a kind of praise)
'twofold on way back' is the wordplay.
'twofold' becomes 'dual' (synonyms).
'on way back' says the letters should be written in reverse.
'dual' back-to-front is 'LAUD'.
(Other definitions for laud that I've seen before include "Praise acclaim" , "Praise - celebrate" , "Praise, magnify" , "'Praise, glorify (4)'" , "Give praise to" .)