Beginning to glean from the past description of fifty years? (6)
I believe the answer is:
golden
'description of fifty years?' is the definition.
(as in a golden anniversary)
'beginning to glean from the past' is the wordplay.
'beginning to' indicates taking the first letters.
'from' says to put letters next to each other.
'the past' becomes 'olden' (I've seen this before).
The first letter of 'glean' is 'g'.
'g'+'olden'='GOLDEN'
(Other definitions for golden that I've seen before include "Halcyon - yellow" , "Most favourable; bright" , "- - wedding (50th)" , "Brilliant" , "With sixteen across Apple variety" .)