Greatly distress husband with quarrel (6)
I believe the answer is:
harrow
'greatly distress' is the definition.
'harrow' can be an answer for 'distress' (something harrowing is distressing). I am unsure of the 'greatly' bit.
'husband with quarrel' is the wordplay.
'husband' becomes 'h' (abbreviation).
'with' means one lot of letters go next to another.
'quarrel' becomes 'arrow' (I've seen this in other clues).
'h'+'arrow'='HARROW'
Can you help me to learn more?
(Other definitions for harrow that I've seen before include "English public school - farm implement" , "Soil-breaker; school" , "Distress greatly - public school" , "Break up (ground) - distress (feelings)" , "Public school - farming implement" .)