Praise former spouse returning lot (5)
I believe the answer is:
extol
'praise' is the definition.
(I know that extol is a kind of praise)
'former spouse returning lot' is the wordplay.
'former spouse' becomes 'ex' (an ex-spouse).
'returning' says the letters should be written backwards.
'lot' back-to-front is 'tol'.
'ex'+'tol'='EXTOL'
(Other definitions for extol that I've seen before include "Praise highly, laud" , "Praise greatly" , "celebrate" , "Cry up" , "Crack up" .)