Clumsy miner discovered dinosaur, looking up, eating quietly (8)
I believe the answer is:
inexpert
'clumsy' is the definition.
(I've seen this before)
'miner discovered dinosaur looking up eating quietly' is the wordplay.
'discovered' indicates the central letters (dis-covered - outer letters removed).
'dinosaur' becomes 'T Rex' (abbreviation for Tyrannosaurus Rex).
'looking up' shows that the letters should be reversed in order (in a down clue, letters go up).
'eating' indicates putting letters inside.
'quietly' becomes 'p' (musical symbol).
The centre of 'miner' is 'ine'.
'trex' in reverse letter order is 'xert'.
'xert' going around 'p' is 'xpert'.
'ine'+'xpert'='INEXPERT'
(Other definitions for inexpert that I've seen before include "with little skill" , "unprofessional" , "Offering little professionally" , "Unskilled" , "Bumbling" .)