About time pilots returning, each a long way off (7,5)
I believe the answer is:
streets ahead
'a long way off' is the definition.
'about time pilots returning each' is the wordplay.
'about' indicates putting letters inside.
'time' becomes 't' (abbreviation).
'pilots' becomes 'steers' (I've seen this in another clue).
'returning' says the letters should be written in reverse.
'each' becomes 'ahead' ('a head' can mean 'per person').
't' placed inside 'steers' is 'steerts'.
'steerts' in reverse letter order is 'streets'.
'streets'+'ahead'='STREETS AHEAD'
(Other definitions for streets ahead that I've seen before include "much better" , "Greatly superior" , "vastly superior" , "immeasurably better" , "A long way in front" .)