Daniel may be fixed ... (6)
I believe the answer is:
'fixed' is the definition.
(I've seen this before)
'daniel may be' is the wordplay.
'may be' is an anagram indicator.
'daniel' is an anagram of 'NAILED'.
(Other definitions for nailed that I've seen before include "Fixed with metal spikes", "Daniel (anag.)", "Fastened with metal pin", "Fixed with pins", "snatched".)