Denny piled ten awkwardly, without assistance (13)
I believe the answer is:
'without assistance' is the definition.
(without depending on others)
'denny piled ten awkwardly' is the wordplay.
'awkwardly' indicates anagramming the letters.
'dennypiledten' anagrammed gives 'INDEPENDENTLY'.
(Other definitions for independently that I've seen before include "Alone and unaided" , "without the help of others" .)