During the weekend, tense individual rocks (6)
I believe the answer is:
stones
'rocks' is the definition.
('stone' can be a synonym of 'rock')
'during the weekend tense individual' is the wordplay.
'during' indicates putting letters inside.
'the weekend' becomes 'SS' (abbreviations for Saturday and Sunday).
'tense' becomes 't' (grammatical abbreviation).
'individual' becomes 'one' (an individual is one person).
't'+'one'='tone'
'ss' placed around 'tone' is 'STONES'.
(Other definitions for stones that I've seen before include "Small pieces of rock" , "''Sticks and ...... may break my bones''" , "Attacks" , "They've been rocking and rolling since the 1960s" , "Pebbles" .)