Praise former spouse, bringing lot back (5)
I believe the answer is:
extol
'praise' is the definition.
(I know that extol is a more specific form of the action praise)
'former spouse bringing lot back' is the wordplay.
'former spouse' becomes 'ex' (an ex-spouse).
'bringing' says to put letters next to each other.
'back' says the letters should be written backwards.
'lot' in reverse letter order is 'tol'.
'ex'+'tol'='EXTOL'
(Other definitions for extol that I've seen before include "Crack up" , "Proclaim" , "Lift up" , "Praise highly, laud" , "Glorify - honour" .)