Give reasons for maybe one dumped on prairie (7)
I believe the answer is:
explain
'give reasons for' is the definition.
(I've seen this before)
'one dumped on prairie' is the wordplay.
'one dumped' becomes 'ex' (a former partner, someone who was dumped).
'on' says to put letters next to each other.
'prairie' becomes 'plain' (I've seen this in another clue).
'ex'+'plain'='EXPLAIN'
'maybe' is the link.
(Other definitions for explain that I've seen before include "Pin axle (anag.)" , "Elucidate, make clear" , "Spell out" , "Tell us how" , "Defend" .)