Speechless, scratching head regarding everything about protective cover (8)
I believe the answer is:
umbrella
'protective cover' is the definition.
(I've seen this before)
'speechless scratching head regarding everything' is the wordplay.
'speechless' becomes 'dumb' (synonyms).
'scratching head' means to remove the first letter (the first letter or head is scratched out).
'regarding' becomes 're' ('re' means regarding or about).
'everything' becomes 'lla' (I can't explain this - if you can you should believe this answer much more).
'dumb' with its initial letter removed is 'umb'.
'umb'+'re'+'lla'='UMBRELLA'
'about' acts as a link.
Can you help me to learn more?
(Other definitions for umbrella that I've seen before include "Gamp" , "Parasol" , "Comprehensive" , "Portable ribbed canopy as rain shelter" , "For protection against the elements" .)