Since you'd like to make one slam try but have no ace to cue bid
, do the best you can by bidding four hearts, showing your strong second suit.
East raised to three diamonds and rather than bid four hearts West decided to look for a diamond slam with a cue bid
of three spades.
You therefore reserve the cue bid
of the suit on your left to show agreement, keeping the bid of the suit on your right as natural.
A cue bid
of four clubs will receive a four heart reply as South cannot cue bid
This is not a cue bid
but agrees spades and says your cards are suitable for a slam, ie good spade support and a sound club suit.
Over the 2 of hearts bid East bid a clear cut 3NT but when West soldiered on with 4 spades a cue bid
of 5 hearts paved the way for an excellent 6 of spade contract.
If partner does not like your clubs four no-trumps will be to play, four of a suit bid will be a cue bid
agreeing the club suit.
South jumps to four spades and with your side silent North cue bids
five clubs, South five diamonds and when North bids five spades South passes.