Capacity of crew seeing across delta (9)
I believe the answer is:
bandwidth
'capacity' is the definition.
(I've seen this before)
'crew seeing across delta' is the wordplay.
'crew' becomes 'band' (both can mean a group of people).
'seeing across delta' becomes 'width' (I can't justify this - if you can you should give a lot more credence to this answer).
'band'+'width'='BANDWIDTH'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for bandwidth that I've seen before include "Particular range of frequencies" , "Informal capacity" , "Range of transmission frequencies" .)