Celebrate without much backing (5)
I believe the answer is:
extol
'celebrate' is the definition.
(I've seen this before)
'without much backing' is the wordplay.
'without' becomes 'ex' (Latin).
'much' becomes 'lot' (I've seen this in other clues).
'backing' is a reversal indicator.
'lot' back-to-front is 'tol'.
'ex'+'tol'='EXTOL'
(Other definitions for extol that I've seen before include "Speak highly" , "Laud; glorify" , "Lift up" , "Pay tribute to" , "trumpet" .)