About to be blocked by referees, half-back’s starting to jog (7)
I believe the answer is:
refresh
'jog' is the definition.
(I've seen this before)
'about to be blocked by referees half-back's starting' is the wordplay.
'about to' becomes 're' (I've seen this in other clues).
'be blocked' means one lot of letters goes inside another (to block can mean to box in or contain).
'by' means one lot of letters go next to another.
'referees' becomes 'refs' ('ref' can be a synonym of 'referee').
'half back's starting' becomes 'h' (I can't justify this - if you can you should believe this answer much more).
'refs' put next to 'h' is 'refsh'.
're' put within 'refsh' is 'REFRESH'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for refresh that I've seen before include "Give new energy to" , "Enliven once more" , "cool" , "Renew" , "Stimulate as by reminding, or top up drink" .)