Layabout was on line after time (7)
I believe the answer is:
wastrel
'layabout' is the definition.
(I've seen this before)
'was on line after time' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to'**).
'line' becomes 'l'.
'after' says to put letters next to each other.
'time' becomes 't'.
're'+'l'='rel'
'rel' after 't' is 'trel'.
'was'+'trel'='WASTREL'
(Other definitions for wastrel that I've seen before include "Person who dissipates resources self-indulgently" , "Spendthrift" , "A useless, good for nothing fellow" , "Layabout" , "Good-for-nothing person" .)