Wary of running feud disrupting almost all aid (7)
I believe the answer is:
heedful
'wary' is the definition.
(I've seen this before)
'running feud disrupting almost all aid' is the wordplay.
'running' indicates an anagram (the letters run around to different places).
'disrupting' means one lot of letters goes inside another (inside letters 'disrupt' the flow of outside one).
'almost all' means to remove the last letter (most but not all of the word).
'aid' becomes 'help' (synonyms).
'feud' with letters rearranged gives 'edfu'.
'help' with its final letter taken off is 'hel'.
'edfu' going inside 'hel' is 'HEEDFUL'.
'of' is the link.
(Other definitions for heedful that I've seen before include "Attentive, listening carefully" , "Attentive - circumspect" , "Wary" , "Prudent" , "Paying careful attention" .)