In fighting mode, slangily

• Hostile behaviour
• Problems and difficulties
• About to blow, in slang
• Bother with a horse, say, otherwise go back
• Provocation (informal)
• Greek consumed by past grief
• Trouble as wrecked Argo ships gallons
• Belligerent, in Britspeak

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
aggro \aggro\ n. 1. aggravation or aggression. [informal British usage] I skipped it because it was too much aggro

WordNet Word definitions in WordNet
n. (informal British usage) aggravation or aggression; "I skipped it because it was too much aggro"