The ornamental design for an adjustablelamp, as shown and described.
FIG. 1 is a front elevational view of an adjustable lamp showing my new design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a front perspective view thereof.
The claimed design is shown in solid lines in the figures. The broken lines shown in FIGS. 5-7 are for illustrative purposes only and form no part of the claimed design.