Definition of tuck up:
(v) :
(transitive) To pull the blankets or duvet up over (someone in bed); to put (someone) to bed.
(v) :
(intransitive) To pull the blankets or duvet up over oneself in bed.
(v) :
(transitive) To push the fabric at the bottom of a garment into itself or under another garment (especially trousers, skirt, dress etc.)
(v) :
(transitive) To cheat, trick or scam (someone).
(v) :
(intransitive, boxing) To protect one's face by covering it with the gloves
(v) :
(intransitive) to bring one's legs and abdomen together while lying face-up on the floor; to perform a tuck-up