Spread for which I’d turned up behind schedule (6)
I believe the answer is:
dilate
'spread' is the definition.
(both can mean to expand)
'i'd turned up behind schedule' is the wordplay.
'turned up' is a reversal indicator.
'behind schedule' becomes 'late' (I've seen this before).
'id' in reverse letter order is 'di'.
'di'+'late'='DILATE'
'for which' acts as a link.
(Other definitions for dilate that I've seen before include "Widen like eye pupils" , "Make wider or larger" , "Widen, distend" , "Widen, spread out" , "Enlarge or widen, like pupils perhaps" .)