Shrub in French art, one less colourful on the outside? (8)
I believe the answer is:
espalier
'shrub' is the definition.
(espalier is a type of shrub)
'french art one less colourful on the outside?' is the wordplay.
'french art' becomes 'es' ('is' in French - 'art' can mean 'is' eg 'thou art').
'one' becomes 'i' (Roman numeral).
'less colourful' becomes 'paler' (I've seen this before).
'on the outside?' is an insertion indicator.
'i' going within 'paler' is 'palier'.
'es'+'palier'='ESPALIER'
'in' acts as a link.
(Other definitions for espalier that I've seen before include "Lattice-work for tree-training" , "Lattice-work for training trees" , "Trellis on which shrubs are trained, like pearlies" , "Trellis to train plants to grow flat" , "Climbing trellis" .)