Clash with dog chewing end of lead (7)
I believe the answer is:
collide
'clash' is the definition.
(I know that clash can be written as collide)
'dog chewing end of lead' is the wordplay.
'dog' becomes 'collie' (collie is a kind of dog).
'chewing' means one lot of letters goes inside another (inserted letters are chewed).
'end of' indicates one should take the final letters.
The last letter of 'lead' is 'd'.
'collie' placed around 'd' is 'COLLIDE'.
'with' acts as a link.
(Other definitions for collide that I've seen before include "Dash together; clash" , "Come into conflict" , "Clash; conflict" , "Crash together" , "Hit" .)