Jar with crow's foot in jelly (8)
I believe the answer is:
vaseline
'jelly' is the definition.
(I know that Vaseline is a type of petroleum jelly)
'jar with crow's foot' is the wordplay.
'jar' becomes 'vase' (vase is a kind of jar).
'with' says to put letters next to each other.
'crow's foot' becomes 'line' (line in one's face).
'vase'+'line'='VASELINE'
'in' is the link.
(Other definitions for vaseline that I've seen before include "Brand of petroleum jelly" , "petroleum product" .)