Cryptic

[terrya]

Disconcert, but only for an instant (5) ??A?E

[Oldred]

phase ?

[Davemano]

Shake

[shoota]

Amaze ?

[elliemay1]

phase sounds good

[shoota]

Erm, 'faze' is good but 'phase' is something else entirely....

[Oldred]

Quite right shoota - please ignore offering

[Davemano]

Phase doesn't mean disconcert.
Shake shows as disconcert, also two shakes is what you say about a moment or instant, therefore an (one) instant is a shake.

[mac44]

Chambers has phase as an alternative spelling for faze and Bradford's has phase listed for disconcert.

[Davemano]

mac obviously dictionaries vary, but can a 'phase' be an instant. Pity we can't see or be told which fits rest of grid.