Large bow in tree (5)
I believe the answer is:
larch
'tree' is the definition.
(larch tree is a kind of tree)
'large bow' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'bow' becomes 'arch' (both can mean to curve).
'l'+'arch'='LARCH'
'in' acts as a link.
(Other definitions for larch that I've seen before include "wood" , "Deciduous conifer" , "Supplier of timber" , "Coniferous tree with deciduous bright green needles" .)