Makes up for having no seat, somehow (6)
I believe the answer is:
atones
'makes up for' is the definition.
(I've seen this in another clue)
'no seat somehow' is the wordplay.
'somehow' is an anagram indicator.
'no'+'seat'='noseat'
'noseat' anagrammed gives 'ATONES'.
'having' is the link.
(Other definitions for atones that I've seen before include "Makes amends using a stone" , "Makes reparation" , "Makes up for injury inflicted" , "Does penance with a stone" , "Makes redress" .)