Spell Combat with a held charge vs casting a spell

My level 1 Magus has cast Shocking Grasp during the first round and missed his touch attack so is still holding the charge. On his second turn, can he use Spell Combat to attack with the spell in his offhand as well as taking a melee attack with his weapon?

Spellstrike (a level 2 feature) is not involved in this question at all. This is about whether Spell Combat can be used without actually casting the spell during the full round action if the spell is already being held in hand. Do I have to literally cast a spell during the full round action in order to qualify for spell combat or would holding a spell charge be enough?

I’ll need a full RAW answer to either confirm or overturn the ruling at the table (which I will not describe in order to leave the answer unaffected).

Note: I understand that at level 2, with spellstrike, I can deliver touch spells through my weapon. However, there is absolutely no interaction between that ability and this question.