Tree's shadow over golf club (7)
I believe the answer is:
dogwood
'tree's' is the definition.
(dogwood is a kind of tree)
'shadow over golf club' is the wordplay.
'shadow' becomes 'dog' (dogging is a kind of shadowing).
'over' says to put letters next to each other.
'golf club' becomes 'wood' (I've seen this before).
'dog'+'wood'='DOGWOOD'
(Other definitions for dogwood that I've seen before include "Flowering shrub" , "timber" , "grows wild" , "Flowering tree" , "Shrub with dark red 5s" .)