Official old men backing one out on the tiles? (6)
I believe the answer is:
'one out on the tiles?' is the definition.
'official old men backing' is the wordplay.
'official' becomes 'ref' (match official in football, say).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'men' becomes 'OR' (Other Ranks: non-commissioned soldiers).
'backing' says the letters should be written in reverse.
'refoor' written backwards gives 'ROOFER'.
(Other definitions for roofer that I've seen before include "eg Thatcher" , "One works on the top of a house" , "Person working on top of a house" , "High-level building worker" , "One putting top on building" .)