Busy time in game’s doubly hard for us (4,4)
I believe the answer is:
rush hour
'busy time' is the definition.
'rush hour' can be an answer for 'time' (rush hour is a kind of time). I'm not certain of the 'busy' bit.
'game's doubly hard for us' is the wordplay.
'game's' becomes 'RU's' (rugby union).
'doubly' indicates the doubling of some letters.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'for us' becomes 'our' ('our' means belonging to us).
'h' duplicated is 'hh'.
'rus'+'hh'+'our'='RUSH-HOUR'
'in' is the link.
Can you help me to learn more?
(Other definitions for rush hour that I've seen before include "It happens at the beginning and end of the working day" , "Time of day when traffic is busiest" , "having battled through this?" , "Weekday crush of people and cars" , "Busy time for travel" .)