Pieces of equipment added in depots, involving everyone (13)

I believe the answer is:

installations

'pieces of equipment added' is the definition.
(pieces of equipment that must be installed)

'in depots involving everyone' is the wordplay.
'depots' becomes 'stations' (I've seen this in another clue).
'involving' means one lot of letters goes inside another.
'everyone' becomes 'all' (all people).
'stations' enclosing 'all' is 'stallations'.
'in'+'stallations'='INSTALLATIONS'

I've seen this clue in The Times.

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