The most common and most likely answer to this crossword clue is the 6 letter word TOTTER
T
O
T
T
E
R
More clues leading to the result TOTTER
Buddy explains!

The straight part
We know that "I add/rock" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case i add/rock = totter.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TOTTER mean?
TOTTER noun- An unsteady movement or gait.
- A rag and bone man.
- To walk, move or stand unsteadily or falteringly; threatening to fall.
- To be on the brink of collapse.
- To collect junk or scrap.