Expand chest, prepared to limit time on run (7)
I believe the answer is:
stretch
'expand' is the definition.
(I've seen this before)
'chest prepared to limit time on run' is the wordplay.
'prepared' is an anagram indicator.
'to limit' means one lot of letters goes inside another.
'time' becomes 't' (abbreviation).
'on' is an insertion indicator (as in clothing 'on' a person).
'run' becomes 'r' (cricket abbreviation).
'chest' with letters rearranged gives 'stech'.
'stech' enclosing 't' is 'stetch'.
'stetch' going around 'r' is 'STRETCH'.
(Other definitions for stretch that I've seen before include "Make demands on; lengthen" , "sort of limousine" , "Elasticity, prison term" , "Term of imprisonment" , "Tax" .)