To summon up is to gather the courage or strength you need. Summon up the nerve.
It takes an abstract object, so people summon up courage rather than anything physical. To summon up a memory is a third use and means deliberately calling it back.
1phrasesummon upTo gather the courage or strength you need.
“It took a fortnight to summon up the courage to ask.”
summon up is a phrase.
Practised in Phrasal Verbs