Bother to pay back, head the other way (6)
I believe the answer is:
nettle
'bother' is the definition.
(I know that bother can be written as nettle)
'pay back head the other way' is the wordplay.
'pay' becomes 'nett' (I've seen this before).
'back head' becomes 'el' (I am not sure about this - if you are sure you should believe this answer much more).
'the other way' shows that the letters should be reversed in order.
'el' written backwards gives 'le'.
'nett'+'le'='NETTLE'
'to' is the link.
Can you help me to learn more?
(Other definitions for nettle that I've seen before include "Clasp it firmly and it will not sting" , "Sting or annoy with the plant" , "To be annoying" , "Irritate, annoy" , "it seems to flower only if dead" .)