See some evidence of streaking in hippy gatherings (4-3)

I believe the answer is:

love-ins

'hippy gatherings' is the definition.

'see some evidence of streaking' is the wordplay.
'see' becomes 'lo' (archaic word meaning 'look!').
'some evidence of streaking' becomes 'veins'.
'lo'+'veins'='LOVE-INS'

'in' is the link.

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.