Tunnel in progress? (5,3)

I believe the answer is:

under way

I believe this is a double definition.

'tunnel' is the first definition.
(I've seen this before)

'in progress?' is the second definition.
(I've seen this before)

(Other definitions for under way that I've seen before include "coming on" , "In motion (nautical)" , "Going" , "In progress" , "Might sewer network be" .)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app