Roofer left in middle of row (5)
I believe the answer is:
tiler
'roofer' is the definition.
(I've seen this before)
'left in middle of row' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in middle of' is an insertion indicator.
'row' becomes 'tier' (tier is a kind of row).
'l' inserted into 'tier' is 'TILER'.
(Other definitions for tiler that I've seen before include "Working man" , "Roof-worker" , "Craftsman" , "Tradesman who covers roofs or bathroom walls with rectangular materials" , "Roofer" .)